LINDA WERTHEIMER, host:
The other major story we're following throughout the morning is the nuclear crisis in Japan. The Japanese military and the Tokyo Fire Department today sprayed tons of water on one of the reactors at the damaged nuclear complex in northern Japan. It was the second day that water cannons were brought in to try to cool down overheated fuel rods.
NPR's Christopher Joyce is in Tokyo following this story and joins us now.
So did the fire trucks help, Chris?
CHRISTOPHER JOYCE: Well, it's a little early to tell, Linda. It seems rather little, but Japanese authorities are pretty happy to report that after they sprayed yesterday the radiation level dropped at the site and some water got into the pool where the used fuel rods are stored.
So today they brought in even more fire trucks - seven of them today, including one from the U.S. military, and they spent half an hour spraying about 50 tons of water on reactor number three. That's the one with the top that's blown off the top of the building. You could see a huge stream of water as each truck drove up and then sprayed the reactor and then moved away to let the next truck in.
And there was a lot of steam - it was quite dramatic - but clearly the building was very hot.
WERTHEIMER: Now, they're also trying to get electrical power back to the complex. Bringing it in from somewhere else?
JOYCE: Yeah, that's progressing. They laid a power cable in and they plan to cycle in electricity from a power company to the north, but there's no electricity yet. There's just the cable. Authorities say they actually don't know when they'll get the electricity, but clearly they desperately need it because they use electricity to get the pumps working. It'll bring more water in.
WERTHEIMER: And the watering operation is aimed at the spent fuel pools? That's the main focus?
JOYCE: Yes. And the reactors themselves appear to be fairly stable for the moment. They shut down when the quake hits - they're automatically set to do that. But what's causing problems was something called decay heat. It's kind of like an electric tea kettle. It takes a while once you unplug it for the heating element to cool off and it seems as if it's cool.
But with spent fuel pools, these fuel rods remain very hot and they're supposed to stay submerged constantly. And apparently several of the pools may have gone dry.
WERTHEIMER: Well, what does that mean? What happens when they go dry?
JOYCE: Well, it hasn't happened very often. So the scenarios that engineers run predict that eventually, if they're dry, they'll overheat. That can create hydrogen that can explode and there can be a fire. And of course the rods are full of radioactive material, so a fire would be very bad.
Although, I must say, experts I've talked to, they're a little puzzled. Because if these pools have dried up, why haven't there been serious fires already and a lot more radiation, like the worst-case scenarios? I mean, it could be that the buildings and the concrete are absorbing the heat or the pools aren't really dry.
And then not all these pools are the same. The way this works is that after five or six years a rod is taken out of the reactor and retired to the pool. At first it's hot and then it gets cool. So each pool has its own mix of really hot rods and and so to speak - and not so hot ones. That could be why they've have so much trouble with one of the reactors - number four. It was shut down for maintenance last November.
And when they do that, they move all the rods from the reactor over to the pool, so that would mean a lot of very hot fuel rods in that pool.
WERTHEIMER: So do we know how much spent fuel is stored at this plant?
JOYCE: Well, I've seen a Tokyo power company document and it says all the pools together contain 1,760 tons of fuel in the six pools, and there's another large pool on the site that's not connected to a reactor. That was a year ago. Those numbers may be different, but still that's a lot - a huge potential source of radiation.
WERTHEIMER: So what are they saying about radiation levels around the plant, around the country?
JOYCE: It's pretty much the same. An American plane flew over the site and there's a lot of radiation there. Beyond the site, there are a few spots where there are elevated levels of radiation, but Japanese authorities are saying none of those hot spots really poses an immediate risk to civilian populations. It's really the workers at the plant who are the ones who are truly at risk here.
WERTHEIMER: We've been talking to NPR's Christopher Joyce. He's in Tokyo. Chris, thank you.
JOYCE: You're welcome. Transcript provided by NPR, Copyright NPR.